Engine starter drive



sept.3,194s. BWJQNES l 2,407,158

ENGINE STARTER DRIVE Filed April 2, 1945 dat@ kvm I N VEN TOR. Bywyv/U@Zones A TOBNEY Patented sept. 3, 194s UNITED STATES PATENT oEFlCE;

Burr W. Jones, Elmira, N. Y., assig'nor to Bendix Aviation Corporation,South Bend, Ind., a corporation of Delaware Application April 2, 1945,Serial N0. 586,199

I aclantis. (o1. vi-n l This invention relates to engine starters of thei class in which a starting motor is automatically coupled to an enginemember for cranking the engine. 1

It is an object of the present invention to provide a novel starter forinternal combustion engines which is dimensionally small withoutsacricing sturdiness and long life.

- It is a further object to provide a simple, compact starter of cleandesign,`the parts` of which can be manufactured by low-cost machiningopyielding member therebetween, thus aiding in reducing the overalldiameter to the minimum.

It is a further object of such a device to provide unitary means forassisting in the disengagement of the starter pinion and preventing thepinion from drifting against the engine member While in the inoperativeposition.

A further object is to provide such a device comprising traversing meanshaving a thread of comparatively large diameter and low helix angle tofacilitate the traversal oi the pinion member.

A further object of such a device is lto provide a starter pinion ofsmall size and driving and supporting means for the pinion whereinbending moments are reduced to a minimum.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation of the device partly in vertical section, theparts being shown in inoperative position;

Fig. 2 is a view similar to Fig. 1 showing the parts in operativeposition; and

Fig. 3 is an expanded view in perspective of the pinion and theactuating means therefor.

In Fig. 1 of the drawing, there is illustrated a power shaft I,journalled in a bearing 2 in the frame 3 of a starting motor. Atraversing and power transmitting member in the form of a sleeve 4,interiorly threaded as shown at 5, is

xedly mounted on the end of the power shaft by means of a bushing 6 xedin the end of thesleeve, and a pin I passing diametrically through thesleeve, bushing and shaft. The pin is retained by any suitable meanssuch as a ring 8 surrounding the sleeve and crimped in place asindicated at 9. An anti-frictionv thrust bearing I0 is preferablyinterposed between the bushing Ii and the motor frame 3. A thimble IIhaving a smooth cylindrical interior surface I2 is threaded Within thesleeve 4 for longitudinal movement therein toward and away from thebushing 6.

A cranking member in the form of a pinion I3 is mounted coaxially withthe sleeve 4 for traversal into and out of engagement with an enginemember suchas a flywheel gear I4. The end of the pinion is reduced indiameter so as to t slidably within the thimble II, and a yieldingdriving connection between the thimble and Dinion is provided in theform of a cylindrical block I5 of elastically deformable material suchas rubber, fitting loosely within said thimble in abutting relationtothe pinion. It it is deemed desirable, the rubber block I5 may bebonded to the adjacent surface of the pinion IB. The mounting means forthe pinion comprises an extension thereof in the form of a stub shaftI'I fixed integrally therein in any suitable manner, as by brazing orWelding, and slidably journalled in a bearing I8 provided in an outboardhousing I9 rigidly mounted on the motor frame 3. A spring 20 is seatedin a cylindrical recess 2l of the stub shaft I'I bearing at its otherend on a fixed closure disc 22 to assist in demeshing the pinion andmaintaining the pinion in demeshed position. .A disc 23 of non-metallicmaterial, preferably fiber, is set into the bushing 6 of sleeve 4 forthe purpose of preventing. noise when the pinion member and .itsassociated parts are thrown back to idle position,V The longitudinalmovement of the pinion into engagement with the .engine gear is limitedby an anti-friction thrust bearing 24 seated against the housing I9 andslidably receiving the stub shaft I1.

In the operation of this device, rotation of the power shaft I and thesleeve 4 by the starting motor causes thimble II, by virtue of itsinertia, to be threaded to the left in Fig. 1, which motion istransmitted through the `rubber block I5 to the pinion I3, causing it tomove into mesh with engine member until stopped by the thrust bearing24. Further movement of the thimble causes the elastic block I5 to beplaced under compression and thereby expands it radially into frietionalContact with the inner surface I2 of the thimble. When the rotation ofthe thimble is thus arrested, it is compelled to rotate with the sleeve4, which rotation is transmitted through the rubber block I5 to thepinion member I 3. Inasmuch as the stub shaft I'I is solidly anixed to 3the pinion and the pinion is forcibly pressed against the thrust bearing24 when power is applied to crank the engine, it is obvious that thepinion will be very rigidly supported in its bearing i8. During thetraversal of the pinion into full mesh with engine gear Ill, thecombination antidrift and demeshing spring 20 is compressed and is heldin the compressed position until the engine starts. When the engine res,the acceleration of the engine gear causes the pinion and: itsassociated parts tooverrun the sleeve 4, where;

by the thimble l I is threaded back to idle position with the assistanceof the spring 20 which demeshes the pinion and holds it in demeshedposition.

As shown in Fig. l, the sleeve 4 encloses the member substantiallyenclosing said block and movable parts oi' the drive sor as to preventUforeign matter such as dust, dirt and grease from` n fouling the Workingparts. l1 for mounting the pinion I3 is solid with the pinion, nointerior bearing is necessary which permits an absolute minimum rootdiameter of the pinion teeth. This feature improves the leverage of thestarting motor on the engine.

It will be seen that there is here provided a sturdy and simple enginestarter drive which is compact and easily assembled, small in size andsure in its operation. Although but one embodiment of the invention hasbeen shown and described in detail, it will be understood that otherembodiments are possible and the parts may be rearranged or altered inproportion without departing from the spirit of the invention asdisclosed in the appended claims.

What is claimed is:

l. In an engine starter drive, a power shaft, a sleeve extension fixedthereon, a thimble threaded in the sleeve, a block of elasticallydeformable material in the thimble, a pinion normally housed within thesleeve and engaging said block, a bearing in which the pinion isslidably journalled for, movement by said thimble out of said sleeveinto mesh with a gear of an engine to be started, and means for limitingthe yprojection of the pinion from the sleeve.

2. An engine starter drive as set forth in claim 1 in which thecompression of the block, due to the screw-jack action of the sleeve andthimble, expands the block into frictional engagement with the interiorof the thimble, and. further including yielding means for returning thepinion to idleA position within the sleeve when the pinion overruns thepower shaft.

3. In an engine starter, a power shaft, a pinion adapted to be driventhereby mounted for movement away from the shaft to engage and crank amember of an engine to be started, and means for actuating the pinionfrom the shaft including a pair of threaded sleeves. one of which isconnected to rotate with the shaft and encloses said pinion when in idleposition, and torquecushioning means for said pinion in the form of ayielding driving connection between the other of said threaded sleevesand thev pinion.

4. An engine starter drive for internal combustion engines including acranking member adapted to engage and crank a member of an engine to bestarted, a motor shaft, means actuated thereby including a pair-ofinterthreaded members for causing engagement of Isaid crank- Since thestub shaftf having means cooperating with the housing member fortraversing the pinion into engagement with the engine member.

6. In an engine starter, a bearing, a cranking *member having anextended bearing portion slidably journalled therein and adapted toengage and crank an engine member, a power shaft, means for actuatingthe cranking member from the power shaft including an elasticallydeformable member adjacent said cranking member, an exteriorly threadedthimble enclosing said elastic member, and a housing member xed to thepower shaft vand having a threaded engagement of low helix angle withsaid thimble for traversal of said cranking member toward said bearingupon acceleration of the power shaft.

7. An engine starter drive comprising a pinion member journalled by anextended portion thereof in an outboard bearing t0 mesh and demesh witha member of the engine to be started, said pinion extension having arecess, a spring having one end seated in said recess and maintainedunder initial compression, tending to demesh the pinion, a motor shaftand a housing sleeve xedly mounted thereon, means including a thimblewithin the sleeve having an inclined connection therewith, andcushioning means in the thimble adapted to engage and transmit thelongitudinal movement of the thimble to the pinion to mesh the .pinionupon acceleration of the motor shaft.

8. .An engine starter drive including an inboard andan outboard bearing,a power shaft journalled in said inboard bearing, a hollow sleeve openat one end and provided with threads of low helix angle on its interiorsurface, said sleeve being xed t0 said power shaft, a pinion memberjournalled in said outboard bearing having an axial recess, a closure ofthe outboard bearing, and a helical spring seated at one end in saidrecess and bearing at its other end against the closure, a block ofelastic material attached to said pinion member, and a thimble infrictional engagement with said block, threaded within said hollowsleeve.

9. An engine starter drive characterized by an inboard and an outboardbearing, said bearings being. adapted to carry axial and radial thrust,a power shaft journalled in said inboard bearing, a pinion memberslidably journalled in said outboard bearing and means actuated by thepower shaft including concentric sleeves having an inclined connectiontherebetween and an elastic block forinitially thrusting said pinionagainst Said outboard bearing and subsequently compressing said elasticblock to apply driving torque to the pinion.

BURR W. JONES.

